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Storm tracker Earthquake technology can be used to pinpoint the location and severity of deep ocean storms, say researchers.

These storms, which are those that occur beyond the continental shelf, play a key role in global climate, say scientists in the journal Geophysical Research Letters.

"They act like eggbeaters, mixing carbon dioxide into the oceans," says Dr Anya Reading of the University of Tasmania, who led the research.

The more stormy the oceans, the more carbon dioxide is mixed into them and the less builds up in the atmosphere.

"The Southern Ocean is terrifically important in this regard," says Reading.

Seismic arrays

Deep ocean storms are often difficult to monitor or observe because aircraft, ships and satellites aren't always in the right place to study them.

In the first study of its kind, Reading and colleagues have used data from seismic arrays, designed to monitor earthquakes, to study these storms.

Winds from the storms generate wave energy that in turn produces signatures picked up in the data.

"We use signal processing techniques to work out what direction that energy came from, and that points us back to where the storm occurred," says Reading.

"This is the first study to look at how deep ocean storms in the Southern Ocean appear when viewed through seismology records."

For example, the authors used data from the Warramunga Seismic Array near Tennant Creek in the Northern Territory, to trace seismic background readings to a location in the ocean.

The researchers were then able to correlate that data with real time observations of storms for that location.

"The main thing we're excited about is that we've honed our analysis techniques so we can pinpoint the location of the storms better that we could before," says Reading.

Southern Ocean storms

Reading and colleagues examined a decade of seismic background data showing the variability of storms in the Southern Ocean.

"We see some intriguing seasonal patterns. Storms were more severe during southern hemisphere winters, it's quietest in autumn, and as anyone living in Hobart knows, it gets windy in spring," says Reading.

"But we can also see that storms were less severe in some years compared to others, so we can use this for making more far reaching studies of how storm severity is changing through time."

The researchers will now sift through seismic records to study how deep ocean storm patterns have changed over time.

They hope to make sense of conflicting data from previous studies of deep ocean storms.

But satellites only fly over the same area of ocean about once every five days, so there's a lack of data resolution.

Another data source, the Waverider Buoy operated by the Bureau of Meteorology and CSIRO at Cape Sorell off the west coast of Tasmania, has shown no significant change in wave heights over the past decade or so.

Reading thinks there's a possibility that storms are in fact getting more severe, but are also tracking a little further south, and so any increase in severity isn't being detected by the buoy.

"We have proposed to use seismic data to address that disparity," says Reading.